Ze'ev Avni, born Wolf Goldstein, led a double life as a Soviet intelligence officer while deeply embedded in the early Israeli state. He is believed to be the only known spy to have successfully infiltrated Mossad, Israel's secret intelligence agency. Despite his clandestine activities, Avni also played a significant role in establishing the mental health program for the Israeli military. His true identity and allegiances remained hidden from colleagues and friends for decades, revealing a story of remarkable deception and complexity.